1. Field of the Invention.
The present invention relates to life raft inflation equipment. In particular, the present invention relates to an improved raft inflation valve which controls the flow of pressurized gas from a pressure vessel to an inflatable life raft.
2. Description of the Prior Art.
Inflatable life rafts have found wide use on ocean-going ships and aircraft. An inflatable life raft offers the advantage of light weight and small size. It is stored in its deflated condition for long periods of time when it is not needed, and yet can be inflated rapidly when it is needed to form a large raft capable of holding relatively large numbers of people.
Inflatable life rafts are inflated using a pressurized inflation gas (such as carbon dioxide, dry air, or nitrogen) which is contained in a pressure tank. When the raft is to be inflated, a valve is actuated by pulling a pull cable which is connected at one end to the valve actuating mechanism in such a manner so as to allow the cable to pull free after the firing mechanism has been actuated. The pull cable is typically connected at its other end to the ship. The pull cable is automatically pulled, therefore, when the raft is thrown overboard or when the ship sinks. The valve opens when actuated to permit the pressurized fluid to expand and fill the life raft.
One highly advantageous raft inflation valve has been the Marada Mark VI valve manufactured and sold by Marada Research and Manufacturing of Chaska, Minn. This valve, two of which are used on the U.S. Navy's 25-man Mark VI raft, is a stainless steel valve with a movable spool. The spool is biased by a spring to maintain the valve in a normally closed position. When the pull cable is pulled, it causes a cam to be rotated, which moves the spool against the spring force to open the valve.
The Marada Mark VI valve has provided very reliable operation at the high pressures, and is capable of being actuated with a relatively low pull force on the pull cable (typically less than 20 pounds). The Marada Mark VI valve, however, because of the intricate design and the relatively large number of high precision parts required, has been expensive to manufacture. In addition, like other raft inflation valves, it has been susceptible to contamination if the source of the inflation gas (in this case dry air) contains dust, dirt particles, or other contaminants.
There has been a continuing need for an improved raft inflation valve which provides ultra-high reliability, has a low actuating force, is not affected by contamination or environmental changes, is easy and relatively inexpensive to manufacture, is relatively light-weight, and is compact. Furthermore, because of a large number of existing problems associated with either marginal valve performance or corrosion related to the improper use of dissimilar metal components (e.g. brass valves and aluminum cylinders) there is a significant need for an improved valve which is capable of retrofitting to existing lift raft inflation systems.